1. Field of the Invention
The present invention relates generally to building structures and, more specifically, to a building system using masonry blocks, grout and open web steel joists.
2. Description of the Related Art
Concrete is the most widely used structural and civil engineering material today. Its applications range from small objects like fence posts to roads, dams, and other massive structures.
The key to concrete's wide structural use is in its inherent strength under compression. Although concrete by itself is very strong in compression, it has limited strength in tension and bending. Thus, it is common practice in forming slab structures, such as building floors, to reinforce the concrete. Most reinforcement is in the form of round-section mild steel. The bond between the concrete and the reinforcement is very important and as a result square twisted bars and ridged "deformed" bars are widely used to increase the bond. Another common technique for strengthening slabs of concrete is to prestress the concrete by placing tensioned steel bars, strands or cables in the slab prior to setting of the concrete so that when set, the prestressed concrete slab will be under constant compression.
Floor slabs and other structural components can be in the category of "precast" in that the concrete does not need to be cast on the construction site. There are some advantages associated with precasting concrete, including the reduction of on-site work in congested locations, and the control of standards of quality and the environment so as to avoid rain, freezing, etc.
A problem exists in certain building construction situations in that, for relatively short spans, it is difficult to obtain and use the heavy equipment which is necessary to lift and place the concrete slabs on their supports. While it is possible to avoid precast structures by casting the slab in place, another problem arises in that forms made of wood or other material must be built in place and the retrieval of the forming structures is very difficult. Moreover, the cost of forming concrete on the site is expensive, although the per unit cost can only be decreased if the form material and methods can be re-used. Nonetheless, forming, pouring and finishing a concrete slab takes special skills and equipment, thus resulting in costs that can be prohibitive unless the building structure is very large so as to afford repetitive forming.
Thus, a need exists for an alternative to precast or cast on-site concrete floor slabs.